Automatic reverse tape recorder

ABSTRACT

An automatic reverse tape recorder comprises a normally closed switch disposed in an automatic reverse circuit. This normally closed switch is operated jointly with the actuation of a recording mode-setting attachment to open the automatic reverse circuit and close a circuit for an automatic stop or end alarm operation or circuits for both operations. As a result, the automatic reverse mechanism is actuated only for the reproduction mode, but not for the recording mode. At the recording mode, the arrival of the terminal end of a tape is detected by an automatic stop or end alarm operation or both operations.

This is a continuation of application Ser. No. 129,165 filed Mar. 10, 1980, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to an automatic reverse tape recorder, and more particularly to an automatic reverse tape recorder which disables an automatic reverse operation during a recording mode.

With an automatic reverse tape recorder, an automatic reverse operation during a recording mode is not desired due to great difficulties taking place in preventing erroneous erase. Even if it is attempted to provide a particular mechanism for preventing erroneous erasure from taking place when an automatic reverse operation is carried out during a recording mode, the arrangement of such mechanism will be extremely complicated, disadvantageously leading to a rise in the cost of a tape recorder and a decline in its reliability.

SUMMARY OF THE INVENTION

It is accordingly an object of this invention to provide an automatic reverse tape recorder having a simple arrangement and capable of being easily handled, and which disables an automatic reverse operation during a recording mode.

To this end, according to this invention a circuit for an automatic reverse operation is opened during a recording mode at the actuation of a recording mode setting attachment, and a circuit for an automatic stop or end alarm or circuits for both operations are closed, thereby enabling either or both of the operations.

It is another object of this invention to provide an automatic reverse tape recorder having a simple arrangement and capable of being easily handled and which also disables the fast forward motion of a tape during a recording mode.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for purpose of illustration only and is not intended as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a plan view of an automatic reverse tape recorder embodying this invention, with a case taken off;

FIG. 2 is an exploded perspective view of a reel rest;

FIG. 3 is a longitudinal sectional view of an assembled reel rest;

FIG. 4 is a schematic top plan view showing the mechanical relationship of a power transmitting mechanism and one-way clutch mechanism;

FIG. 5 is a block circuit diagram indicating the action of a magnetism-sensitive element;

FIG. 6 is a top plan view showing the mechanical relationship of a plunger, cam board, pinch roller-supporting board and tape fast forward (hereinafter abbreviated as "FF") lever;

FIG. 7 is a top plan view indicating the action of the cam board;

FIG. 8 is a top plan view showing the action of a head-supporting board;

FIG. 9 is a fractional front view on line IX--IX of FIG. 8 of the head-supporting board;

FIG. 10 is a top plan view indicating the mechanical relationship of an eccentric pin and the head-supporting board;

FIG. 11 is a sectional view on line XI--XI of FIG. 10;

FIG. 12 is a top plan view showing the mechanical relationship of the head-supporting board and a motor polarity changeover switch;

FIG. 13 is a sectional view on line XIII--XIII of FIG. 12;

FIGS. 14A to 14D are block diagrams indicating the action of the motor polarity changeover switch;

FIG. 14E is a schematic servo circuit for the motor polarity changeover switch;

FIG. 15 is a top plan view showing the mechanical relationship of the plunger, cam board, pinch roller-supporting board, tape FF lever and head-supporting board;

FIG. 16 is a top plan view showing the positions of the pinch roller-supporting board and head-supporting board when the tape FF lever is actuated;

FIG. 17 is a right side view of a locking mechanism, before an engagement lever is pressed, showing that a movable chassis is in a rising position;

FIG. 18 is a right side view of the locking mechanism, while the engagement lever is pressed;

FIG. 19 is a perspective view of the locking mechanism, after the engagement lever is pressed, showing that the movable chassis is in a falling position;

FIG. 20 is a perspective view of an erase head, before a push lever is pressed;

FIG. 21 is a perspective view of the erase head, when a recording mode has been arranged by pressing the push lever;

FIG. 22 is a top plan view of a stopper board, before the push lever is pressed;

FIG. 23 is a top plan view of the stopper board, after the push lever is pressed;

FIG. 24 is a fragmental side view of a cassette located by locating pins 332, 333 (not shown) and 334;

FIG. 25 is a bottom plan view showing the mechanical relationship of a main switch of an electric circuit and the movable chassis;

FIG. 26 is a side view on line XXVI--XXVI of FIG. 25;

FIG. 27 is a perspective view of a tape recorder case;

FIG. 28 is a perspective view of an upper half case showing the inside thereof;

FIG. 29 is a block circuit diagram showing the action of an FF switch and a program switch; and

FIGS. 30 and 31 are block circuit diagrams showing the operation of an automatic reverse prevention switch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an automatic reverse tape recorder 10 of this invention comprises a movable chassis 16 rotatably fitted to a fixed chassis 14 by means of a pair of rotation pins 11, 12. As in the Staar system, the movable chassis 16 rises upward in a rotated state when a locking mechanism 20 is released by the insertion of a cassette 18. When the movable chassis 16 rises, the cassette 18 is supported on a reel mechanism 22. A rotation torque is transmitted from a motor 24 to the reel mechanism 22 by means of a motive power-transmitting mechanism 26. A head-supporting board 30 carrying a pair of recording-reproduction heads 27, 28 is rotatably fitted to the fixed chassis 14. The paired recording-reproduction heads 27, 28 may be each of the 4-track 2-channel type and are spaced from the rotation center of a head-supporting board 30 at the same distance. A rotatable cam board 32 designed to rotate the head-supporting board 30 for the alternate push of the paired recording-reproduction heads and a plunger mechanism 34 are also mounted on the fixed chassis 14. A rotatable pinch roller-supporting board 40 is also mounted on the fixed chassis 14 at a point above the head-supporting board 30. This pinch roller-supporting board 40 is provided at one end with a pinch roller 38 for clamping a tape with the aid of a capstan shaft 36 set on the movable chassis 16. A tape FF lever 42 is also provided on the fixed chassis 14. When the pinch roller-supporting board 40 is rotated to retract the pinch roller 38, then the tape FF lever 42 effect the quick run of a cassette tape. An erase head 44 is retractively set on the fixed chassis 14, which is also fitted with an erase head changeover mechanism 46 for controlling the forward and backward movements of the erase head 44. In addition to the above-mentioned mechanical parts, a head circuit changeover switch 48 and motor polarity changeover switch 50 are mounted on a printed circuit board (not shown) disposed below the fixed chassis 14. Further, a tape running direction-instructing switch 52 is mounted on the fixed chassis 14. There will now be described the constituent parts of the aforesaid various mechanisms and other mechanisms.

Now, viewed from the direction in which the cassette is inserted into the tape recorder, that is, the right side of FIG. 1, the direction in which a tape is run from the left to the right is referred to as "a forward direction". The opposite direction in which the tape travels from the right to the left is referred to as "a reverse direction".

As apparent from FIG. 1, the reel mechanism 22 comprises a pair of reel rests 60, 160, which obviously act as a tape feed or a tape take-up member alternately in accordance with the direction in which the motor is driven. Description is now given of the reel rest 60 acting, for example, as a tape feed member at the time of the forward run of a tape.

As seen from FIGS. 2 and 3, the reel rest 60 comprises a threaded and flanged reel shaft 62 provided with an axially extending slit, and a reel base 66 having a key (not shown) engageable with the slit, and fitted to the reel shaft 62 by means of one-way clutch mechanism 64. A magnetic ring 68 provided with a plurality of alternately arranged N and S poles is fitted around the peripheral wall of the reel base 66. A drive pawl 72 is threadedly engaged with the external or male thread portion of the reel shaft 62 by means of a compression spring 70. The reel shaft 62 is loosely fitted around the peripheral wall of a gear shaft 75 of a reel gear 74 constituting part of the later described motive power-transmitting mechanism 26. The reel gear 74 is securely fitted to the gear shaft 75 by means of a collar 76. A nut 78 (FIG. 3) is threadedly engaged with the male thread portion of the lower end section of the gear shaft 75 to fix the reel rest 60 to the movable chassis 16. A snap ring 82 is fitted into an annular groove 80 (FIG. 2) formed in the peripheral wall of the free end of the gear shaft 75 to fix the reel base 66 to the reel shaft 62.

The one-way clutch mechanism 64 comprises a clutch plate 83, in the peripheral edge of which three spiral notches are cut out equiangularly, a felt plate 84 disposed between the clutch plate 83 and reel base 66, and three steel balls 86 (FIG. 2) received in the respective spiral notches of the clutch plate 83. The steel balls are chosen to have such a dimension as can be loosely moved through a free space defined between the inner peripheral wall 87 of the reel gear 74 and the spiral notches of the clutch plate 83.

As shown in FIG. 4, the reel rest 160 acting as a tape take-up member in the above-mentioned case has the same construction as the aforesaid tape feed reel rest 60, except that the spiral notches of the clutch plate 83 are extended in the opposite direction to those of the tape feed reel rest 60, and the magnetic ring 68 is omitted. The constituent parts of the tape take-up reel rest 160 are denoted by reference numerals formed by adding the number 100 to the reference numerals representing the corresponding constituent parts of the tape feed reel rest 60.

With the automatic reverse tape recorder of this invention, the rotation torque of the motor 24 is transmitted by means of a motor pulley 90 (FIG. 4) to the capstan shaft 36 and reel shafts 62, 162 through the motive power-transmitting mechanism 26 comprising a series of gears, without passing through an idler lever, etc. as is the case with the prior art automatic reverse tape recorder. As shown in FIG. 4, the motive power-transmitting mechanism 26 comprises a capstan gear 92 fitted to the capstan shaft 36, a pair of reel gears 74, 174 respectively fitted to the reel shafts 62, 162, and an intermediate gear 94 positioned between the capstan gear 92 on one hand and reel gears 74, 174 on the other. The rotation torque of the motor 24 is transmitted by means of the motor pulley 90 to the capstan shaft 36 through a flywheel 96 and then to the reel gears 74, 174 through the capstan gear 92 and intermediate gear 94. The rim of the flywheel 96 is fitted with a rubber tire 98.

When the motor pulley 90 of the motor 24 is rotated counterclockwise of FIG. 4, then the capstan shaft 36 and reel gears 74, 174 are all rotated clockwise. Where, with the tape feed reel rest 60, the reel gear 74 is rotated clockwise, then the steel balls 86 run away toward a larger space due to the contact with the inner peripheral wall 87 of the reel gear 74 and are rotated idly between the inner peripheral wall 87 and clutch plate 83, giving rise to no friction therebetween. As a result, the clutch plate 83 and consequently the reel base 66 and reel shaft 62 are not obviously rotated. Conversely with the tape take-up reel 160, the steel balls 186 tightly contact the inner peripheral wall 187 of the reel gear 174 and are moved toward a small space to perform a wedging action. Since, at this time, a frictional force appears between the inner peripheral wall 187 of the reel gear 174 and the clutch plate 183, the steel balls 186 cause the clutch plate 183 to be rotated clockwise. The rotation of the clutch plate 183 leads to the rotation of the reel base 166 by means of the felt plate 184. As a result, the reel rest 160 takes up a tape.

Where the motor pulley 90 is rotated clockwise (not shown), then the clutch plate 83, felt plate 84, and reel base 66 are rotated by the reverse operation from that described above, causing the reel rest 60 to take up a tape.

As mentioned above, the motive power-transmitting mechanism 26 comprises the capstan gear 92, intermediate gear 94, and reel gears 74, 174. Even where the reel gears 74, 174 corresponding to the tape take-up reel rest 60 and tape feed reel rest 160 are rotated at the same time, the one-way clutch mechanism 64, 164 allow only the reel rest 60 or 160 acting as a tape take-up member to be rotated. Where, therefore, the rotating direction of the single motor 24 is reversed, the forward or reverse run of a tape can be easily ensured.

The rotation of the motor 24 is reversed at the detection of a tape end and further as often as required. A magnetism-sensitive element 100 is provided, as shown in FIGS. 1 and 4, adjacent to the magnetic ring 68. The magnetism-sensitive element 100 and the magnetic ring 68 constitute tape end detecting means. This magnetism-sensitive element 100 causes either of the paired recording-reproduction heads to be pushed when the reversion of the run of the motor 24 is detected. To describe in greater detail, the magnetism-sensitive element 100 detects changes in the waveform of pulses issued from the pulse-generating magnetic ring 68 provided with a plurality of alternately arranged N and S poles, and produces an output signal. This output signal is successively processed, as shown in FIG. 5, by a signal-processing circuit 102, logic circuit 104, and plunger driving circuit 106 in the order mentioned, eventually actuating the plunger mechanism. As a result, the head-supporting board 30 is rotated, causing either of the paired recording-reproduction heads to be pushed alternately. The pulse-generating magnetic ring 68 for issuing pulses to the magnetism-sensitive element 100 is fitted to the peripheral wall of the reel body 64. However, the motor pulley 90 may be concurrently used as a magnetic ring. This arrangement reduces a number of parts required and facilitates the assembly of the whole automatic reverse tape recorder. In such case the magnetism-sensitive element 100 should obviously be set adjacent to the motor pulley 90.

As seen from FIGS. 1 and 6, the plunger mechanism 34 comprises a plunger 110 and plunger body 112 which is connected to a plunger-driving circuit 106 and through which a plunger reciprocates. The free end of the plunger 110 has a flat upper surface 113, which is fitted with one end of a coupling board 114 for transmitting the reciprocation of the plunger 110 to a cam board 32 for rotating a head-supporting board 30. To describe in greater detail, a pin 116 erected at one end of the coupling board 114 extends through a hole formed in the flat surface 113 of the plunger 110. The coupling board 114 is fitted to the plunger 110 by means of a snap ring (not shown). The pin 116 passes upward through the coupling board 114. A plunger arm 118 having a long groove which is disposed above the coupling board 114 and allows for the reciprocation of the pin 116 is movably mounted on the fixed chassis 14 adjacently to the plunger 110. A guide groove 120 having a triangular cross section is formed in the surface of the plunger 110 to guide its reciprocation in a state prevented from being rotated.

As apparent from FIG. 6, a pinch roller-supporting board 40 is disposed between the plunger arm 118 and coupling board 114. The pinch roller-supporting board 40 is mounted on the fixed chassis 14 by causing the upward extending integral collar of the supporting board 40 to be loosely fitted around a shaft 121 erected on the fixed chassis 14 and also fitting a snap ring to the shaft 121. A torsion coil spring 188 is fitted around the shaft 121 to impart a counterclockwise urging force to the pinch roller-supporting board 40. One end of the torsion coil spring 188 is pressed against the lateral face of the later described eccentric pin 197. The pinch roller 38 is rotatably fitted to one end of the pinch roller-supporting board 40, the other end of which is provided with a notch 123, against which the pin 122 of the tape FF lever 42 is pressed. A projecting attachment 124 is mounted on the pinch roller-supporting board 40 between the cam board 32 and plunger arm 118. Erected on the upper surface of the projecting attachment 124 is a pin 126 fitted into a groove formed in the 2-pronged free end of the plunger arm 118. As seen from FIG. 6, the pinch roller-supporting board 40 holding the pinch roller 38 has one end shaped like the letter T, both ends of whose bar are constituted by downward bent portions 128, 129.

To avoid complication of the drawing, the shaft and pin acting as a rotation center are particularly marked with the symbol in other drawings than FIG. 1.

As apparent from FIG. 7, a downward extending pin 130 is erected at the other end of the coupling board 114. A tension coil spring 131 is stretched between the pin 130 and fixed chassis 14. This tension coil spring 131 presses the pin 130 against the lateral wall of the heart-shaped cam groove 132 of the cam board 32. The heart-shaped cam groove 132 comprises a pair of lobes 135, 136 and a pair of corners 133, 134. Both lobes 135, 136 jointly define a V-shaped junction 137. Where a tape is run in the forward direction and the recording-reproduction head 27 is pushed, the pin 130 is pressed against the lobe 133.

A larger pin 138 and smaller pin 139 project from the upper surface of the cam board 32. A torsion coil spring 142 acting as a toggle spring is stretched between the larger pin 138 and a pin 140 erected on the fixed chassis 14. The cam board 32 is rotatably fitted to the fixed chassis 14 by means of a rotating pin 144. In the condition indicated in FIG. 7, the junction 137 of the paired lobes 135, 136 is set below an imaginary line extended between the pin 144 acting as a rotation center and the pin 130. The cam board 32 comprises an integrally formed 2-prong projecting attachment 148. A movable contact 149 of a tape run direction-instructing switch 52 is fitted into a long groove of the projecting attachment 148. The switch 52 comprises a pair of fixed contacts 150, 151 with a movable contact 149 set therebetween. A connection between the movable contact 149 and either of the paired fixed contacts 150, 151 closes the tape run direction-instructing circuit, causing either of a pair of lamps (not shown) indicating the forward and backward running of a tape to be lighted.

The head-supporting board 30 rotated by the cam board 32 comprises, as shown in FIGS. 8 and 9, an adjustment leaf spring 190, both ends of which are turned slightly upward. The recording-reproduction heads 27, 28 (only 27 is indicated to avoid the complication of representation) are set above both upturned ends of the adjustment leaf spring 190. The recording-reproduction head 27 is set in place by mounting a fitting board 192 attached to the underside of the recording-reproduction head 27 on one of both upturned ends of the adjustment leaf spring 190, and fitting both ends of the fitting board 192 to the head-supporting board 30 by means of screws 193, 194. The inclination and displacement of the recording-reproduction head 27 are prevented by holding two washers 195 to define the level at which the recording-reproduction head 27 is to be fixed and controlling the threaded engagement of the other screw 194. The leaf spring 190 slightly turned upward at both ends enables the azimuth of the recording-reproduction head to be adjusted easily and over a broad range.

The head-supporting board 30 is fitted to the fixed chassis 14 by means of a screw 196 in a state rotatable about the screw 196. A pair of locating eccentric pins 197, 198 are equidistantly arranged on both sides of the rotatable screw 196 to adjust the position of the recording-reproduction head when pushed at the rotation of the head-supporting board 30. As shown in FIGS. 10 and 11, the eccentric pin 198 has its upper surface provided with a slot and its lower portion formed into a male-threaded screw. The slotted surface and male-threaded lower portion are concentrically arranged. An annular groove 199 is formed at the central part of the eccentric pin 198, with the peripheral wall of the groove 199 pressed against the lateral side of the head-supporting board 30. The center line of the eccentric pin 198 is displaced from that of the annular groove 199 for a distance e. Since, as mentioned above, the annular groove 199 is displaced from the male-threaded lower portion of the eccentric pin 198 fitted to the fixed chassis 14, the rotation of the slotted surface of the eccentric pin 198 causes that plane of the eccentric pin 198 which abuts against the head-supporting board 30 to be widely displaced, though the eccentric pin 198 itself remains unchanged in position. Accordingly, the horizontally pushed position of the recording-reproduction head 27 or 28 can be reliably adjusted over a broad range without increasing a free space occupied by the eccentric pin 198. Since the head-supporting board 30 is located in a position spaced from the center 196 by the engagement with the annular groove 199 on the eccentric pin 198, the position of the head-supporting board 30 after rotating may be maintained with accuracy, and the contact surfaces of the head and tape can be held in a predetermined position. The contact position between the head and tape face may be adjusted by rotating the eccentric pin 198. Thus, the head can be given a constant pad pressure to ensure steady tape run. The head-supporting board 30 inserted into the annular groove 199 has its height defined by the condition in which the eccentric pin 198 is threadedly engaged with the fixed chassis 14. Therefore, the level at which the recording-reproduction head 27 or 28 is set above the head-supporting board 30 can be adjusted by the annular groove 199 of the eccentric pin 198. Also the vertical shaking of the head-supporting board 30 itself can be prevented because the thrust or upward pressing force on the head-supporting board 30 is arrested by the annular groove 199. Since the eccentric pin 198 serves also as a thrust bearing, desired location and vertical shaking prevention can be achieved with a minimal number of parts and simple construction. Another eccentric pin 197 is obviously shaped like the eccentric pin 198.

As apparent from FIG. 8, the head-supporting board 30 comprises an integrally formed 2-pronged protuberance 200 engageable with the pin 139 erected on the cam board 32, and lever-like projections 202, 203 formed on both sides of the rotation center of the head-supporting board 30. These lever-like projections 202, 203 act as actuating levers for actuating the head circuit changeover switch 48 or motor polarity changeover switch 50.

There will now be described the motor polarity changeover switch 50 by reference to FIGS. 12 and 13. This motor polarity changeover switch 50 comprises one set of a single movable contact 204 and paired fixed contacts 206, 207 and another set of a single movable contact 204 and paired fixed contacts 206, 207. When the recording-reproduction head 27, for example, is pushed, the movable contact 204 having an elasticity of its own has a property of touching one fixed contact 206 but not the lever-like projection 203. Where the head-supporting board 30 is rotated clockwise of FIG. 8 to push the other recording-reproduction head 28, then the movable contact 204 is forcefully moved to touch the other fixed contact 207 by means of the lever-like projection 203. The head circuit changeover switch 48 has the same property and is operated in the same manner as the motor polarity changeover switch 50. In the foregoing embodiment, the head circuit changeover switch 48, motor polarity changeover switch 50 and tape run direction-instructing switch 52 were separately arranged. However, it is possible to provide a single switch designed concurrently to changeover the head circuit and motor polarity and also instruct the tape run direction.

As illustrated in FIGS. 14A to 14D, the electrical circuit of the motor polarity changeover switch 50 can drive a motor in the normal or reverse direction by means of a motor control circuit 108. The constant rotation speed of a motor for both forward and reverse reproductions can be effected by making a comparison between a value obtained by detecting the actual number of rotations of the motor and a control target value designed to set the motor rotation at the prescribed speed and carrying out such control (namely, servo control) as minimizes a possible difference resulting from the comparison. A servo circuit used for this particular purpose may be formed of the known type shown in FIG. 14E. For the above-mentioned object, the switch 51 is released as shown in FIGS. 14A, 14B to apply servo control, thereby effecting the forward and reverse rotations with the rotation speed of a motor always rendered constant. The acceleration of the rotation speed of a motor for the FF and REW modes of a tape run is carried out by setting a control value at a higher level than a maximum number of rotations of a motor, and releasing the servo control to let the motor run at a maximum speed. To this end, the switch 51 is closed as shown in FIGS. 14C and 14D to effect the FF and REW modes of a tape run. As mentioned above, the servo control is applied or stopped by the changeover of the operation of the switch 51, and the operation of the motor polarity changeover switch 50 is shifted, thereby making it possible to effect the forward and reverse reproductions, and the FF and REW modes of a tape run simply by driving a single motor. Therefore, the object of letting the single motor run at a constant speed and controlling its high speed normal and reverse rotations is attained by a simple arrangement. An automatic reverse tape recording embodying this invention which is free from a complicated mechanical arrangement can be operated with high reliability and manufactured at low cost. Where the motor is to be driven in the reverse direction, it is preferred that the motor be started a prescribed length of time after the end of its normal run in order to prevent its possible damage occurring at the start of its reverse rotation.

As shown in FIG. 6, a tape FF lever 42 is rotatably fitted by means of a snap ring to a rotatable pin 210 mounted on the fixed chassis 14. This tape FF lever 42 is provided at one end with a pin 122 engageable with a notch 123 formed in the pinch roller-supporting board 40. The tape FF lever 42 comprises an attachment 212 which is bent vertically downward (toward the backside of the drawing) and formed at the outer end of the tape FF lever 42, triangular hole 214 and elongated groove 216. The lever attachment 212 projects out of a case 218 in which the fixed chassis 14 and movable chassis 16 are received. Disposed in the triangular hole 214 is a pin 224 erected at the free end of a coupling board 222 movably fitted to the fixed chassis 24 by means of a rotatable pin 220. One end of a torsion coil spring 226 wound about the rotatable pin 220 is pressed against the pin 224 so erected as to project out of the triangular hole 214. The pin 220 is urged toward the apex 227 of the triangular hole 214, thereby ensuring the neutral position of the tape FF lever 42. Where the lever attachment 212 is rotated in the direction of A indicated in FIG. 6, then the pin 224 is pressed against the corner 229 of the triangular hole 214. Where the lever attachment 212 is rotated in the direction of B indicated in FIG. 6, then the pin 224 abuts against the corner 228 of the triangular hole 214. A movable contact 232 of a motor fast drive switch 230 is fitted into the elongated groove 216. While remaining in a neutral position as shown in FIG. 6, the movable contact 232 touches neither of the fixed contacts 233, 234.

There will now be described the alternate push of the recording-reproduction heads 27, 28 by the rotation of the head-supporting board 30. Now let it be assumed that the recording-reproduction head 27 is pushed and a tape is running in the forward direction. Where, in this case, the run of the motor 24 is reversed either by the hand, if necessary, or automatically by the detection of a tape end, then the magnetism-sensitive element 100 detects changes in the waveform of pulses issued from the magnetic ring 68. As a result, the plunger 110 is moved inward for the prescribed distance against the urging force of the tension spring 131 by the joint action of the signal-processing circuit 102, logic circuit 104 and plunger drive circuit 106. Where the recording-reproduction head 27 is pushed, then the pin 130 of the coupling board 114 is urged as shown in FIG. 7, to the corner 133 of the heart-shaped cam groove 132. As a result, the junction 137 of the paired lobes 135, 136 is positioned below an imaginary line extending between the pin 130 and the rotation center 144 of the cam board 32. Where, therefore, the plunger 110 is moved inward, then the pin 130 of the coupling board 114 moving with the plunger 110 is guided through the right lobe 135 of the heart-shaped cam groove 132 to press the end wall of the right lobe 135, thereby causing the cam board 32 to be rotated counterclockwise about the rotation center 144. Where the cam board 32 is rotated counterclockwise, the movable contact 149 is pressed against the other fixed contact 151 by means of the 2-pronged projection 148. As a result, a display lamp instructing the reverse run (right to left run) of a tape is lighted. With the counterclockwise rotation of the cam board 32, the pin 139 of the cam board 32 is engaged with the 2-pronged projection 200. As a result, the head-supporting board 30 is rotated clockwise about the rotation center 196 (FIG. 8), until the board 30 touches the eccentric pin 197, thereby causing the recording-reproduction head 28 to be pushed. This eccentric pin 197 is constructed in the same manner as the eccentric pin 198 and can adjust the pushed position of the recording-reproduction head 28 and the level at which the head 28 is to be fitted. As apparent from FIG. 8, where the head-supporting board 30 is rotated clockwise, the lever-like projections 202, 203, respectively press the movable contacts of the head circuit changeover switch 48 and motor polarity changeover switch 50, causing the movable contacts to abut against the other fixed contact against their elastic force. The changeover of the operation of the switches 48, 50 establishes a head circuit for the recording-reproduction head 28 and reverses the polarity of the motor 24.

After the recording-reproduction head 28 is pushed, the pin 130 of the coupling board 114 is urged, as shown in FIG. 15, by the force of the tension spring 131 (FIG. 7) to be pressed against the lower corner 134 of the heart-shaped cam groove 132. The coupling board 114 and plunger 110 are brought back to a projecting position by the urging force of the tension spring 131. At this time, the V-shaped junction 137 of the lobes 135, 136 of the heart-shaped cam groove 132 is set below an imaginary line extending between the erected pin 130 and the rotation center 144 of the cam board 32. Where, therefore, the plunger 110 is moved inward against the urging force of the tension spring 131, then the pin 130 is guided through the left lobe 136 of the heart-shaped cam groove 132 to press the end wall of the lobe 136. Accordingly, the cam board 32 is rotated clockwise, and the head-supporting board 30 is rotated counterclockwise, until the board 30 abuts against the eccentric pin 198. Therefore, the recording-reproduction head 27 shown in FIG. 8 is again brought to a projection state. At this time the coupling board 114 occupies the position indicated in FIG. 7.

The fast forwarding of a tape during its forward and reverse runs is effected by the rotation of the tape FF lever about the rotation center 210 (FIG. 6). Referring to FIG. 6, the REW operation during the forward run of a tape is carried out by rotating the lever attachment 212 in the direction A. Where the lever attachment 212 is rotated in the direction of A or B, the pin 224 is shifted from the neutral position in which the pin 224 is pressed against the wall of the apex 227 of the triangular hole 214 to the tape FF position in which the pin 224 abuts against the corner 229 or 228 of the triangular hole 214. Where the lever attachment 212 is rotated, as shown in FIG. 16, in the direction A for the REW operation, then the pin 122 of the tape FF lever 42 is moved clockwise along the surface of the left side portion of the notch 123 while pressing the wall thereof. As a result, the pinch roller-supporting board 40 is rotated clockwise about the rotation center 121 (FIG. 6), causing the pinch roller 38 to be separated from the capstan shaft 36. The downward bent attachment 128 or 129 of the end portion of the pinch roller-supporting board 40 to which the pinch roller 38 is fitted is always positioned very close to part of the head-supporting board 30 even when the recording-reproduction head 27 or 28 is in a pushed state. The downward bent attachments 128, 129 are set at a level the same as or lower than the head-supporting board 30. Referring to FIG. 16, therefore, in which the recording-reproduction head 27 is pushed, the retract of the pinch roller-supporting board 40 due to the rotation of the lever attachment 212 in the direction A causes the downward bent lever attachment 129 to abut against the head-supporting board 30. As a result, the board 30 is slightly rotated clockwise about the rotation center 196 (FIG. 8). At this time, the pushed recording-reproduction head 27 is slightly retracted. A tape which is not contacted by the retracted recording-reproduction head 27 can be run fast forward smoothly. The tape FF lever 42, head-supporting board 30 and pinch roller-supporting board 40 occupy the positions indicated in one dot-dash line in FIG. 16, after the tape FF lever 42 is rotated in the direction A. Under such condition, the pin 224 is pressed against the corner 229 of the triangular hole 214 (FIG. 15) by the urging force of the torsion coil spring 188. Where the tape FF lever 42 is rotated in the direction B of FIG. 15 showing the pushed recording-reproduction head 28, then the pin 122 is rotated counterclockwise along the surface of the right side portion of the notch 123, when pressing the wall of the notch 123. As a result, the head-supporting board 30 is slightly rotated counterclockwise about the rotation center 196 (FIG. 8) to retract the recording-reproduction head 28. While this case represents the REW operation, the pin 224 is pressed against the corner 228 of the triangular hole 214 (FIG. 6). At this time, the lever attachment 212 is rotated in the same direction as that in which a tape is fast forwarded. If, therefore, the recording-reproduction head 27 is pushed, the REW operation is carried out by rotating the lever attachment 212 in the direction A, and the tape FF operation is effected by rotating the lever attachment 212 in the direction B. Conversely where the recording-reproduction head 28 is pushed, then the tape FF operation is carried out by rotating the lever attachment 212 in the direction A, and the REW operation is realized by rotating the lever attachment 212 in the direction B.

When the plunger 110 is moved inward, the plunger pin 116 is guided through the elongated groove of the plunger arm 118 to press the wall of the end of the elongated groove, thereby causing the plunger arm 118 to rotate counterclockwise about the rotation center 240 (FIG. 6). When the 2-pronged free end of the plunger arm 118 is engaged with the pin 126 of the pinch roller-supporting board 40, then the pinch roller-supporting board 40 is rotated clockwise against the urging force of the torsion coil spring 188. The tape FF lever 42 is normally subject to the urging force of the torsion coil spring 226 (FIG. 15) for causing the pin 224 to be pressed against the wall of the apex 227 of the triangular hole 214, namely, urged toward the neutral position. When the pinch roller-supporting board 40 is rotated clockwise, then the pin 122 is disengaged from the notch 123. Therefore, the tape FF lever 42 is rotated with the clockwise rotation of the pinch roller-supporting board 40. As a result, the pin 224 is pressed against the wall of the apex 227 of the triangular hole 214 to occupy a neutral position. Thus, the tape FF mode is released, at the moment the polarity of the motor 214 is changed.

As shown in FIG. 17, the locking mechanism 20 of the movable chassis 16 comprises an engagement lever 242 movably fitted to the fixed chassis 14 and engagement cam 244 rotatably fitted to the fixed chassis 14. The engagement lever 242 has a pair of crosswise extending elongated holes 245, 246. Guide pins 247, 248 fixed to a pair of attachments extending downward from the side walls of the fixed chassis 14 are detachably inserted into the elongated holes 245, 246 by means of the snap ring. The guide pins 247, 248 are pressed against the right side walls of the corresponding elongated holes 245, 246 by the urging force of a tension coil spring 249 stretched between the fixed chassis 14 and engagement lever 242. An engagement pin 250 is erected on the side wall of the engagement lever 242. The inner end of this engagement lever 242 constitutes a cam surface 251. Reference numeral 252 of FIG. 17 denotes a push button fitted to the outer end of the engagement lever 242. The engagement cam 244 is rotatably fitted to a bent attachment extending upward from the side wall of the fixed chassis 14 by means of a rotatable pin 254, and is urged counterclockwise of FIG. 17 by a torsion coil spring 256 wound about the rotatable pin 254. The engagement cam 244 comprises a pair of cam surfaces 257, 258 and three engagement grooves 259, 260, 261. An engagement pin 264 engageable with the engagement groove 260 of the engagement cam 244 when the movable chassis 16 is lifted is provided on one lateral side of the movable chassis 16 which faces the engagement cam 244. A movable guide roller 266 is mounted on the other lateral side of the movable chassis 16 which faces the engagement lever 242. The guide roller 266 is loosely fitted about the periphery of an erected pin 268. The movable chassis 16 is urged upward by a tension spring 270 stretched between the movable chassis 16 and a bent attachment extended upward from one lateral side of the fixed chassis 14. Another tension spring 270 is provided, as shown in FIG. 20, in a symmetric position on the other lateral side of the fixed chassis 14.

Where the push button 252 is pressed to bring down the movable chassis 16, then the engagement lever 242 is pressed against the urging force of the tension spring 249, while being guided by the guide pins 247, 248, until the left end walls of the elongated holes 245, 246, respectively abut against the guide pins 247, 248. During the initial stage of the stroke by which the engagement lever 242 is pressed, the engagement pin 250 of the engagement lever 242 slides along the periphery of the cam surface 257 of the engagement cam 244. As a result, the engagement cam 244 is rotated clockwise about the rotation center 254 against the urging force of a torsion spring 256. The clockwise rotation of the engagement cam 244 causes the engagement pin 264 of the movable chassis 16 to be disengaged from the engagement groove 260 of the engagement cam 244. At this time, the cam surface 251 of the engagement lever 242 is pressed against the guide roller 266 of the movable chassis 16, causing the movable chassis 16 to be rotated against the urging force of the tension spring 270 counterclockwise about the rotation center (FIG. 1), namely, to be pressed downward. Accordingly, the engagement pin 264 is brought to a position facing the cam surface 258 (FIG. 18). Where the stroke of pressing the engagement lever 242 further proceeds, the guide roller 266 is moved further downward along the cam surface 251 of the engagement lever 242 against the urging force of the tension spring 270. At this time, the engagement pin 264 of the movable chassis 16 is guided along the cam surface 258. Where the stroke of pressing the engagement lever 242 is brought to an end, then the engagement pin 264 is inserted into the engagement groove 261, thereby letting the tension spring 270 have a full urging force. As a result, the movable chassis 16 is brought to a fallen position as shown in FIG. 19. The stroke of pressing the engagement lever 242 is stopped when the guide pins 247, 248, respectively abut against the left end walls of the elongated holes 245, 246. At the end of the stroke, the engagement pin 250 is received in the engagement groove 259, causing the tension spring 249 to have a full urging force.

Where, in FIG. 19 showing the fallen movable chassis 16, a release lever 278 movably mounted on the fixed chassis 14 by means of a rotatable pin 276 is rotated by the insertion of a cassette, then the movable chassis 16 is lifted. In other words, when inserted, the cassette presses on an upward bent attachment 280 (FIG. 19) formed at one end of the release lever 278. As a result, the release lever 278 is rotated clockwise about a rotation center 276. The tip of the other end portion of the release lever 278 is disposed fully apart from the rotation center 254 of the engagement cam 244, and one lateral side of the other end portion of the release lever 278 is set adjacent to the lateral side of the engagement cam 244. The upward bent attachment 280 itself is fully removed from the rotation center 276. Even where, therefore, the insertion of a cassette slightly presses the upward bent attachment 280, then a great rotation torque is applied to the engagement cam 244. Accordingly, when the upward bent attachment 280 of release lever 278 is pressed, however slightly, by the inserted cassette, the engagement cam 244 is immediately rotated clockwise as seen in FIG. 19. As a result, the engagement pin 264 of the movable chassis 16 is released from the engagement groove 261. At this time, the engagement pin 264 slides along the cam surface 258 by the urging force of the tension spring 270 which has been accumulated by the stroke of pressing the engagement lever 242 to rotate the engagement cam 244 and then is inserted into another engagement groove 260. The movable chassis 16 is lifted with the movement of the engagement pin 264 and brought to rest when the engagement pin 264 is inserted into the engagement groove 260.

Like the tension spring 270, the tension spring 249 stretched between the engagement lever 242 and fixed chassis 14 has its urging force fully accumulated during the stroke by which the engagement lever 242 is pressed. Therefore, a force for clockwise rotating the engagement cam 244 is transmitted from the engagement pin 250 to the cam surface 257. When the engagement pin 264 is released from the engagement groove 261, the engagement cam 244 is rotated by an urging force transmitted from the tension spring 249 through the engagement pin 250, as well as by an urging force applied from the tension spring 270 to the engagement pin 264. As a result, the engagement pin 250 is brought back to a state disengaged from the engagement groove 259. The engagement lever 240 regains a projecting position by the fully accumulated urging force of the tension spring 249.

With the above-mentioned locking mechanism 20, the urging force of the tension spring 270 is accumulated by the stroke of pressing the engagement lever 242. The movable chassis 16 is lifted by the accumulated urging force of the tension spring 270. Therefore, the pressing force applied by the insertion of a cassette well serves the purpose, even if it is small. Therefore, it is unnecessary to apply a great force to a cassette when it is inserted. When, therefore a mechanically weak cassette such as a microcassette is fitted into the tape recorder, the movable chassis 16 can be lifted without the damage or destruction of such cassette. Further, two engagement grooves 260, 261 are formed in a single engagement cam 244. The movable chassis 16 is lifted or lowered by the different modes of engagement between the engagement pin 264 between the engagement grooves 260, 261. This arrangement renders the construction of the locking mechanism 20 simplified and compact, and provides a shockproof engagement. The movable chassis 16 is lifted by engagement between the engagement groove 260 and engagement pin 264. If, therefore, the tension spring 270 used has a small tension constant, it is obviously possible to let the spring 270 have a fully accumulated urging force when the movable chassis 16 is to be brought down.

While the recording-reproduction head 27 is pushed, as shown in FIG. 16, the lever-like projection 203 of the head-supporting board 30 is not disposed above the engagement lever 242. When pressed, therefore, by a stroke, the engagement lever 242 does not abut against the lever-like projection 203. In contrast, where the head-supporting board 30 is rotated clockwise to cause the recording-reproduction head 28 to be pushed, then the lever-like projection 203 protrudes beyond the engagement lever 242, as shown in FIG. 15. In this case, the projection 203 is positioned adjacent to the forward wall of the stepped portion 282 of the engagement lever 242 (FIG. 17). Where, therefore, the engagement lever 242 is pressed to eject a cassette with the recording-reproduction head 28 kept in a pushed state, then the stepped portion 282 of the engagement lever 242 presses the lever-like projection 203 to rotate the head-supporting board 30 counterclockwise, thereby pushing the other recording-reproduction head 27. If the recording-reproduction head 27 is pushed, as described above, when the engagement lever 242 is pressed to eject a cassette, then the head 27 is left in situ. If the recording-reproduction head 28 is pushed when the engagement lever 242 is pressed, then the recording-reproduction head 27 is now pushed by the rotation of the head-supporting board 30. Therefore, the recording-reproduction head 27 never fails to be pushed after a cassette is ejected. Where the cassette is again inserted into a tape recorder 10 in case of need, recording and reproduction can always be carried out by the head 27.

As shown in FIGS. 1 and 20, the tape recorder 10 comprises an erase head operation changeover mechanism 46 which pushes the erase head 44 at the time of recording and retracts it at the time of reproduction.

The tape recorder 10 is used as part of, for example, a car stereophonic system. The erase head operation changeover mechanism 46 is provided with an erase head operation changeover push lever 290 for actuating an amplifier switch (not shown). As seen from FIG. 20, the push lever 290 has an elongated hole 292 formed in the upper surface and another elongated hole 293 provided on the lateral side. The pins 295, 296 of the fixed chassis 14 are loosely fitted into the elongated holes 292, 293 by means of a snap ring. A tension coil spring 300 is stretched between an upward bent attachment 297 provided on the lateral side of the push lever 290 and an upward bent attachment 298 formed on the lateral side of the fixed chassis 14. The pins 295, 296 are respectively pressed against the left side walls of the elongated holes 292, 293 by the urging force of the tension coil spring 300. The erase head 44 is mounted on a head-fitting board 304 by means of two screws 302, 303. The head-fitting board 304 is rotatably mounted on the fixed chassis 14 by means of a rotatable pin 306. One end of a torsion coil spring 308 wound about the pin 306 is pressed against the screw 303, causing the head-fitting board 304 to be urged clockwise. The screw 303 is pressed against a bent attachment 311 formed on the push lever 290. Since the tension coil spring 300 has a greater urging force than the torsion coil spring 308, the head-fitting board 304 is rotated counterclockwise, and the erase head 44 is retracted, as shown in FIG. 20, at the fall of the movable chassis 16. An engagement pin 310 is fitted to the lateral side of the push lever 290. Two notches 312, 313 are formed in the upper edge of the lateral side of the movable chassis 16 for engagement with the engagement pin 310. The notch 312 is formed at such a point as allows for the engagement of the engagement pin 310, when the movable chassis 16 is lifted without pressing the push lever 290. The other notch 313 is formed at such a point as allows for the engagement of the engagement pin 310, when the movable chassis 16 is lifted by pressing the push lever 290 against the urging force of the tension coil spring 300, until the pins 295, 296 are respectively pressed against the right end walls of the elongated holes 292, 293.

The push lever 290 has a projecting attachment 317 formed on the inner lateral wall. The projecting attachment 317 is fitted with the later described guide pin 324. An automatic reverse stop switch 315 fitted to a printed circuit board (not shown) is set inside of the projecting attachment 317. The automatic reverse stop switch 315 is a normally closed type provided in the plunger driving circuit 106 which acts as a portion of an automatic reverse circuit, and is rendered nonconducting when the push lever 290 is pressed inward. The switch 315 has a movable contact disposed inside of the projecting attachment 317 of the push lever 290. When the push lever 290 is pressed, the projecting attachment 317 is pressed against the movable contact to release it from the fixed contact, thereby rendering the switch 315 nonconducting.

The engagement pin 310 and notches 312, 313 have the relative positions defined as described above. Where, therefore, a cassette is inserted into the tape recorder 10 without pressing the push lever 290 to release the locking mechanism 20 and the movable chassis 16 is lifted by the urging force of the tension spring 270, then the engagement pin 310 is inserted into the notch 312. Under this condition, the erase head-fitting board 304 is rotated counterclockwise by the urging force of the tension coil spring 300. The erase head 44 which is retracted at this time does not abut against a tape. Therefore, it is possible to carry out only the reproduction mode, but not the recording mode. If, under this condition, an attempt is made to press the push lever 290 by mistake, the engagement pin 310 of the push lever 290 is inserted into the notch 312, thereby preventing the push lever 290 from being pressed. Consequently, the erasing of a tape which might otherwise occur by erroneous operation during reproduction can be completely prevented. As mentioned above, reproduction alone can be carried out under the normal condition. Recording can be effected only by pressing the push lever 290 to push the erase head 44 for contact with a tape. For the recording mode, the push lever 290 is pressed for the prescribed distance, that is, until the pins 295, 296 respectively abut against the right side walls of the elongated holes 292, 293 against the urging force of the tension coil spring 300. Where the movable chassis 16 is lifted by inserting a cassette in the tape recorder 10 with the push lever 290 pressed, then the engagement pin 310 is inserted into the notch 313 of the movable chassis 16. Where, at this time, the push lever 290 is pressed backward, then the bent attachment 311 is also retracted. As a result, the urging force of the torsion spring 308 is given a full play, causing the head-fitting board 304 to be rotated clockwise about the rotation center 306 (FIG. 21). Accordingly, the erase head 44 is set in the prescribed projecting position for contact with the surface of a tape, thereby effecting its erase. The angle through which the head-fitting board 304 is rotated clockwise to determine the prescribed projecting position of the erase head 44 is defined by a bent stopper 314 (FIG. 1) extending above the fixed chassis 14. This stopper 314 also acts a member against which the other end of the torsion spring 308 is pressed.

Where the push lever 290 is pressed for the recording mode, then the projecting attachment 317 of the push lever 290 is jointly moved inward to abut against the movable contact of the normally closed switch 315 to detach it from the fixed contact, thereby opening the plunger-driving circuit 106. When the plunger-driving circuit 106 is opened, then an automatic reverse tape run is made impossible, thereby preventing recording from being effected on the opposite plane of a tape.

Generally, a reliably accurate vertical level of a tape is ensured on the A side of a cassette, whereas the level can not be realized on the B side thereof. With the foregoing embodiment of this invention, forward recording is made possible only when a cassette is inserted into the tape recorder 10 with the A side kept upward. At this time, recording can be effected with tones of good quality. It is considered necessary to stop the operation of a program switch during the recording mode.

An automatic reverse operation during a recording mode is disabled by a switch interlocking with a recording mode-setting attachment such as the above-mentioned push lever 290. The detection of the arrival of the terminal end of a tape during the recording mode can be carried out, as shown in FIG. 30, by the steps of actuating the switch 315 by the push lever 290 to close a buzzer-driving circuit 400 during the recording mode, processing an output signal from a magnetism-sensitive element 100 in the buzzer-driving circuit 400 and energizing an end alarm by a buzzer 402. The arrival of the terminal end of a tape can also be detected by applying the known automatic stop device wherein the switch 315 closes a switching circuit 404 during the recording mode, as shown in FIG. 31. The arrival of the terminal end of a tape can be further detected by a system wherein the end alarm and automatic stop operation are jointly applied.

As described above, the automatic reverse tape recorder of this invention comprises a normally closed switch means disposed in an automatic reverse circuit. At the reproduction mode, an automatic reverse circuit is closed, enabling an automatic reverse operation upon receipt of a signal denoting the detection of the terminal end of a tape. Where the recording-setting attachment is actuated, the switch means is jointly operated to open the automatic reverse circuit and close a circuit for an automatic stop or end alarm stop or circuits for both operations. A signal denoting the arrival of the terminal end of the tape enables an automatic stop or end alarm operation or both operations. With the foregoing embodiment, the recording mode-setting attachment is formed of a push lever 290. However, it is unnecessary to restrictively use the lever 290. Any type of recording mode-setting attachment obviously will serve the purpose, provided it opens or closes a prescribed circuit as need arises. Where, with the automatic reverse tape recorder of this invention, the recording mode-setting attachment is actuated, an automatic reverse operation is reliably disabled, eliminating the necessity of carrying out any other operation and consequently elevating the operability of the automatic reverse tape recorder as a whole. For the recording mode, for example, the operation of a switch means has only to be changed over jointly with the actuation of the recording mode-setting attachment, thereby simplifying the arrangement of the automatic reverse tape recorder. With this invention, the arrival of the terminal end of the tape during the recording mode is not detected by the automatic reverse operation, but by the application of the automatic stop or end alarm operation or both operations, thereby eliminating any room for the occurrence of erroneous erase. 

What is claimed is:
 1. In an automatic reverse cassette tape recorder wherein a playback mode is set by the loading of a cassette and, after the ejection of the cassette by means of an ejection means, a new playback mode is set on a determined one side of the cassette, which comprises: a magnetic tape driving motor selectively for driving a magnetic tape in first and second running directions; an operator actuable recording mode-setting member; a pair of magnetic heads; support means for supporting said pair of magnetic heads spaced from each other; an automatic reverse circuit including an end of tape detecting means for detecting the terminal end of a tape and generating an electrical signal indicating detection of the end of the tape; means responsive to at least one of said end of tape detecting means and said recording mode-setting member for bringing one of the paired magnetic heads to a projected position suitable for contact with a magnetic tape; and cassette ejecting means for ejecting a cassette and for causing a prescribed magnetic head to be brought to said projected position only when the prescribed one of the paired magnetic heads is not in said projected position for contact with the tape, thereby always causing said prescribed magnetic head to be projected to a position suitable for contact with the tape when a cassette is ejected by said ejecting means;the improvement comprising: means responsive to operation of said recording mode-setting device for causing said driving motor to operate in only one direction to drive a magnetic tape in said one direction to permit recording on only one side of said cassette; means coupled to said end of tape detecting means for supplying said electrical signal to said magnetic tape driving motor for selectively automatically causing said driving motor to run the magnetic tape in the direction opposite to the previous running direction; an end alarm circuit coupled to said automatic reverse circuit and including a sounding device, said end alarm circuit being selectively actuated upon detection of the magnetic tape end so as to sound said sounding device; an automatic stop circuit coupled to said automatic reverse circuit and being selectively actuated upon detection of the magnetic tape end so as to stop the magnetic tape driving motor; and switch means included in said automatic reverse circuit, said switch means being coupled to said recording mode-setting device, to said automatic reverse circuit, to said end alarm circuit and to said automatic stop circuit, said switch means being always operated upon actuation of said recording mode-setting device to always disable said automatic reverse circuit and to always enable at least one of said end alarm circuit and said automatic stop circuit when the tape recorder is set in the recording mode by actuation of said recording mode-setting device, thereby permitting recording on the tape only when running in said one direction and always preventing recording on the tape when the tape runs in the reverse direction of running of the tape, and permitting playback of the tape in both of said first and second tape running directions under the control of said automatic reverse circuit when said recording mode-setting device is not actuated.
 2. The automatic reverse tape recorder of claim 1, wherein said switch means is a normally closed switch means and which is opened upon actuation of said recording mode-setting device.
 3. The automatic reverse tape recorder of claim 1, wherein said end alarm circuit includes means for turning off the tape recorder upon detection of said magnetic tape end only when said recording mode-setting device is actuated to place the tape recorder in the recording mode.
 4. The automatic reverse tape recorder of claim 1, wherein said end alarm circuit sounds said sounding device only when said magnetic tape end is detected while the tape recorder is in the recording mode as a result of actuation of said recording mode-setting device.
 5. The automatic reverse tape recorder of claim 1, wherein said switch means enables both said end alarm circuit and said automatic stop circuit upon actuation of the recording mode-setting device. 